The majority of mammals rely heavily on chemical signals in regulating social, sexual and aggressive behaviors as well as neuroendocrine status. Research is described which will provide fundamental information on chemical communication in a model animal, the guinea pig (Cavia porcellus). The primary goal of the proposed studies is to understand the interacting roles of the main olfactory system and the accessory olfactory system. Recent research in our laboratories and others suggests that the anatomically distinct accessory system plays a critical role in the reception of sexually-related signals. However, the main olfactory system seems also to be involved in processing this information. The first series of experiments will test the hypothesis that the accessory olfactory system is involved in mediating the motivating or rewarding function of biological odors. The second related set of studies will explore the effects of elimination of accessory olfactory function very early in life on animals' behavior and neuroendocrine functions in infancy and adulthood. A third series of studies will examine factors which influence glucose metabolism and hence neural activity within the accessory olfactory system using the 14C 2-deoxyglucose method. The data obtained, while basic in nature, could have long-term relevance to programs that control breeding of pest species and to increase efficiency of breeding in commercially valuable species.